A patient undergoing a medical procedure may be positioned in one of four positions: (1) the supine position, in which the patient is positioned on his or her back with his or her legs straight or bent, (2) the prone position in which the patient is face down, (3) the lateral position in which the patient is positioned on one side, or (4) the dorsal lithotomy position in which the patient is positioned on his or her back with his or her legs elevated in stirrups. Surgery is carried out using one of a variety of approaches. Common approaches for urological surgery include perineal, abdominal, or flank approaches.
Medical surgery tables should be capable of supporting a patient in any of these four positions while providing for convenient access by the surgeon to the surgical area from between the patient's legs, from either of the patient's sides, or from the patients back or abdomen. Additionally, these tables also should be substantially radiolucent so as to allow obstruction free radiographic imaging from a variety of angles.
Radiographic imaging during surgery is normally carried out using an portable fluoroscopic unit comprised of an x-ray transmitter and an x-ray image intensifier (i.e. receiver) positioned at either side of a large C-shaped arm. To use the image intensifier, the C-shaped arm is positioned around the portion of the patient sought to be imaged. X-rays are directed at that portion of the patient by the x-ray transmitter, pass through the body, and are received by the x-ray receiver. A typical image intensification unit is mounted on a set of wheels, so that the unit may be rolled into position for imaging and then rolled out of the surgical field to allow the surgical procedure to proceed.
One type of table used during medical procedures is a general surgery table having a patient support board which extends from the head of the table to the foot of the table. Lithotomy holders, leg boards, or other supports may be mounted to steel side rails on the table and angled outward from the side rails.
General surgery tables can present problems during procedures requiring image intensification. Their structure includes many radio-opaque components, including steel side rails which extend from the head of the table to the foot of the table. Because x-rays cannot pass through metal, the number of views which can be taken of the desired area is limited to those which would not necessarily include the side rails within the imaging field. This necessarily excludes many oblique-angle images from the range of views available to the surgeon.
Many general surgery tables are pedestal tables. A table of this type includes a back board for supporting the patient. The back board is mounted to a pedestal rising vertically from the floor. The pedestal table provides convenient surgical access to the perineal area of the patient by the surgeon, because the back board of the table extends only to the region of the patient's hips, allowing the surgeon to stand or sit between the separated legs of the patient and to thus directly face the perineal area.
Pedestal type tables present additional problems with respect to image intensification. Because the pedestals utilized in these tables are configured to balance and support the patient's weight, they extend fairly broadly beneath the back board. Since the bases occupy a large portion of the space beneath the patient, they prevent access to a large percentage of the patient's body by the C-shaped image intensification units. Moreover, as with the other general surgery tables, the metal construction of the base and table components interferes with x-ray imaging.
Another difficulty which can be encountered during use of prior art medical tables is found during lateral positioning, and involves the means by which the patient is maintained in the lateral position. Prior art tables utilize a variety of devices for securing the patient on his or her side. Some tables require the use of flexible "bean bags" which are packed around the patient's mid-section while the patient is manually held in a lateral position. Once the bean bags are in position, vacuum suction is used to withdraw air from the bean bags so that they become rigid to support the patient in the lateral position.
A second technique for maintaining a patient in a lateral position involves the use of a padded vice-like device mounted to the side rails of the table. The vice includes a pair of padded plates, each mounted to one side of the table. The patient's mid-section is positioned between the two padded plates, is slightly compressed between them, and is thereby prevented from rolling out of the lateral position.
These prior art devices for holding a patient in the lateral position introduce radio-opaque components into the imaging field and thus limit the use of x-rays during the procedure. Moreover, these devices can be difficult to use because the patient must be manually held on his or her side while the bean bags or other clamping devices are positioned and tightened to hold the patient in the lateral position. Finally, the rigidity of these devices may result in postoperative paresthesia, and pressure points which can result in development of post operative nerve palsies can develop during use of these devices.
For supine, dorsal lithotomy, and prone positioning, chest and kidney pads are frequently used to support the chest and the abdominal regions of the patient. These pads are also used to support the abdominal region during lateral positioning. Because a large portion of the patient's weight is supported by each of these pads, the pressure of the patient's body against the chest and kidney pads may cause complications during procedures long in duration. Such complications can include decubitus ulcers, bruises and lacerations, and nerve palsies which can result in numbness or paralysis of the patient's extremities.
It is therefore desirable to have a medical table for use in medical procedures (including imaging, urological and gynecological procedures, and other medical or surgical procedures) which provides convenient access by the surgeon to the surgical area regardless of whether the patient is in the supine, dorsal lithotomy, prone, or lateral position, which has simple means for safely and reliably securing the patient in any position, and which enables convenient and obstruction-free x-ray imaging of the surgical area.